This invention relates generally to remote measurement of electrical current. More particularly, this invention relates to techniques for measuring electrical current at a one location and using optical signals output from an interferometer to signals indicative of the electrical current to another location for processing.
Prior art for sensing electrical current with optical telemetry includes utilizing a step-down transformer connected to a fiber-wrapped PZT phase modulator through a resistor, with the fiber comprising one leg of a fiber optic Michelson interferometer. Prior art also includes use of Bragg gratings, in changing the spectrum of light telemetered light from the current sensor, as well as fiber optic sensors that make use of the Faraday effect, which change the polarization state of light propagating through an optical fiber in proportion to a magnetic field. These methods tend to be costly to implement and environmentally sensitive, especially when the interferometer is comprised of optical fiber.